Detailed Notes: The Valeo units have what is called a "floating stator", meaning that when the unit is assembled the rotor is not pressed into the alternator castings like a conventional alternator, but is placed/centered in the housing and held in place by the pressure of the through bolts holding the entire assembly together. If these units are dropped, or are subject to pressure during installation,the stator can actually shift slightly which will cause noises that range from a magnetic type 'hum' to a metal-on-metal noise.